Selenium produce blank page after clicking on button

I kept trying to to fulfil text box using selenium but always cannot find that text box after clicking on button to add new customer , it always shows a blank white page. I tried it through chrome and firefox @Test public void AddContact() throws InterruptedException {

         WebElement contacts = driver.findElement(By.xpath("//span[text()='Contacts']"));
           contacts.click();
         WebElement newContact = driver.findElement(By.xpath("/html/body/div[1]/div/div[2]/div[2]/div/div[1]/div[2]/div/a/button"));
         Actions action = new Actions(driver);
         action.moveToElement(newContact).build().perform();
           newContact.click();
           
          WebDriverWait wait = new WebDriverWait(driver, 30);
           wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath("/html/body/div/div/div[2]/div[2]/div/div[2]/form/div[1]/div[1]/div/div/input")));
           
        WebElement firstName = driver.findElement(By.xpath("/html/body/div/div/div[2]/div[2]/div/div[2]/form/div[1]/div[1]/div/div/input"));